Add 'Create patch file' shell script

3-create-patchfile.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+# Create a patch file from winecfg code changes in the subdirectory b.
+
+LC_ALL=C diff -Burp a/programs/winecfg/ b/programs/winecfg/ | grep -vi '^only in' > wine-staging_winecfg.patch